arm/arm64: vfio: Add PCI Express Capability Structure
It turns out that some Linux drivers (like Realtek R8169) fall back to a
device-specific configuration method if the device is not PCI Express
capable:
[ 1.433825] r8169 0000:00:00.0 enp0s0: No native access to PCI extended config space, falling back to CSI
Add the PCI Express Capability Structure and populate it for assigned
devices, as this is how the Linux PCI driver determines if a device is PCI
Express capable.
Because we don't emulate a PCI Express link, a root complex or any slot
related properties, the PCI Express capability is kept as small as possible
by ignoring those fields.
Reviewed-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
Link: https://lore.kernel.org/r/20210713170631.155595-5-alexandru.elisei@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
diff --git a/include/kvm/pci.h b/include/kvm/pci.h
index 42d9e1c..0f2d5bb 100644
--- a/include/kvm/pci.h
+++ b/include/kvm/pci.h
@@ -46,6 +46,8 @@
#define PCI_DEV_CFG_SIZE_EXTENDED 4096
#ifdef ARCH_HAS_PCI_EXP
+#define arch_has_pci_exp() (true)
+
#define PCI_CFG_SIZE PCI_CFG_SIZE_EXTENDED
#define PCI_DEV_CFG_SIZE PCI_DEV_CFG_SIZE_EXTENDED
@@ -73,6 +75,8 @@
};
#else
+#define arch_has_pci_exp() (false)
+
#define PCI_CFG_SIZE PCI_CFG_SIZE_LEGACY
#define PCI_DEV_CFG_SIZE PCI_DEV_CFG_SIZE_LEGACY
@@ -143,6 +147,24 @@
u8 next;
};
+struct pci_exp_cap {
+ u8 cap;
+ u8 next;
+ u16 cap_reg;
+ u32 dev_cap;
+ u16 dev_ctrl;
+ u16 dev_status;
+ u32 link_cap;
+ u16 link_ctrl;
+ u16 link_status;
+ u32 slot_cap;
+ u16 slot_ctrl;
+ u16 slot_status;
+ u16 root_ctrl;
+ u16 root_cap;
+ u32 root_status;
+};
+
struct pci_device_header;
typedef int (*bar_activate_fn_t)(struct kvm *kvm,
@@ -188,6 +210,8 @@
u8 min_gnt;
u8 max_lat;
struct msix_cap msix;
+ /* Used only by architectures which support PCIE */
+ struct pci_exp_cap pci_exp;
} __attribute__((packed));
/* Pad to PCI config space size */
u8 __pad[PCI_DEV_CFG_SIZE];
diff --git a/vfio/pci.c b/vfio/pci.c
index 7784212..ea33fd6 100644
--- a/vfio/pci.c
+++ b/vfio/pci.c
@@ -12,6 +12,11 @@
#include <assert.h>
+/* Some distros don't have the define. */
+#ifndef PCI_CAP_EXP_RC_ENDPOINT_SIZEOF_V1
+#define PCI_CAP_EXP_RC_ENDPOINT_SIZEOF_V1 12
+#endif
+
/* Wrapper around UAPI vfio_irq_set */
union vfio_irq_eventfd {
struct vfio_irq_set irq;
@@ -623,6 +628,12 @@
return PCI_CAP_MSIX_SIZEOF;
case PCI_CAP_ID_MSI:
return vfio_pci_msi_cap_size((void *)cap_hdr);
+ case PCI_CAP_ID_EXP:
+ /*
+ * We don't emulate any of the link, slot and root complex
+ * properties, so ignore them.
+ */
+ return PCI_CAP_EXP_RC_ENDPOINT_SIZEOF_V1;
default:
pr_err("unknown PCI capability 0x%x", cap_hdr->type);
return 0;
@@ -694,6 +705,13 @@
pdev->msi.pos = pos;
pdev->irq_modes |= VFIO_PCI_IRQ_MODE_MSI;
break;
+ case PCI_CAP_ID_EXP:
+ if (!arch_has_pci_exp())
+ continue;
+ ret = vfio_pci_add_cap(vdev, virt_hdr, cap, pos);
+ if (ret)
+ return ret;
+ break;
}
}
